The reaction of aminopropyl trialkoxysilanes with alkyl isothiocyanates is known from A. Baigozhin, Zh. Obshch. Khim. 43 (1973), p. 1408 (C.A. 79: 66463r), which results in N, N'-disubstituted thioureas of the formula EQU (RO).sub.3 Si--(CH.sub.2).sub.3 --NH--CS--NH--R',
in which:
R=ethyl and PA1 R'=phenyl, allyl. PA1 R represents alkyl with 1 to 6 carbon atoms, cycloalkyl with 5 to 7 atoms or aryl PA1 R.sup.1 represents hydrogen or ##STR2## R.sup.2 represents an alkylene group having 1 to 4 carbon atoms, especially --CH.sub.2 --CH.sub.2 --, or arylene, especially 1,2-phenylene, PA1 b represents 0,1 or 2, preferably 0
A symmetric N, N'-substituted compound is described by M. G. Voronkov et al. in Zh. Obshch. Khim. 54 (1984), p. 1098 (C.A. 101: 192031j).
It is obtained by means of the reaction of aminopropyl trialkoxysilanes with thiourea EQU ((RO).sub.3 Si--(CH.sub.2).sub.3 --NH--CS--NH--(CH.sub.2).sub.3 --Si(OR).sub.3).